I'm having an issue when trying to set Thimbleweed Park into fullscreen mode, where it stretches beyond the bounds of my monitor, regardless of my resolution or DPI settings in Windows 7, the only change I saw being that at 1080p, a bit more of the image stays within the bounds, but not enough.

I've tried looking at my NVidia control panel's settings for scaling, but that didn't do anything.

Managed to find the solution on my own. Gonna keep my thread here for others who might experience the same thing.

It was just a case of Discord's overlay causing it to not fullscreen correctly. Also, GOG Galaxy's overlay seemed to cause stuttering in the game, though I could not get 100% sure on that.